HEALTH CONSULTATION ADDENDUM
BURNING GROUND AREAS AT
WOMPATUCK STATE PARK
HINGHAM, MASSACHUSETTS
In the November 1997 sampling episode, EPA collected four sediment samples, three surface
water samples, one drinking water sample, and seven surface soil samples. These samples were
analyzed for semivolatile organics and explosives. Table 1 summarizes this data. The compounds
and concentrations detected in the analysis are summarized in Tables 2 through 4. From the
analysis, PAHs, phthalates, and few other semivolatile organic compounds were found in soil and
water samples at low concentrations.
To decide if a public health hazard exists, ATSDR compared the results with U.S. EPA Region 3's health-based screening values as shown in Tables 2 through 4 and considered the likely scenarios for public exposure. ATSDR also considered the derivation of the screening values that are based on 30 years of exposure for at least 250 days per year (an industrial scenario because the area is not a residential neighborhood).
The reported concentrations were below the screening values in all samples except the following:
| - | Sample WP108 had a 9,10-anthracenedione soil concentration of 1.6J mg/kg (J=estimated
quantity). A screening value for this compound is not available. 9,10-Anthracenedione is
in a class of semivolatile organic compounds called polycyclic aromatic hydrocarbons
(PAHs). Although a screening value is not available for this compound, ATSDR assumed
its toxicity to be as great as the most toxic PAH, benzo[a]pyrene with a screening value of
0.78 mg/kg. Because the screening value is based on 30 years of exposure, 250 days/year
and the sample location is in a fenced area restricting public access, this soil sample with
this concentration does not present an apparent public health hazard. |
| - | Benzeneacetic acid (or more commonly know as phenylacetic acid) was found in samples
WP101 (water) and WP113 (soil) at 5J µg/L and 12J mg/kg, respectively. A screening
value for this compound is also not available. Phenylacetic acid occurs naturally in
Japanese peppermint oils and rose oils and is used in the production of perfumes and
penicillin. Toxicologic data on this compound is limited to several LD50s (1500 mg/kg to
2300 mg/kg) and one nonlethal oral exposure study (450 mg/kg). The concentrations in
these studies were 1000 to 20,000 times greater than expected human doses. Compared
with other compounds, the LD50s are considered "slightly toxic" (University of Nebraska-Lincoln 1997 and University of Florida 1996) but these LD50s do not necessarily represent
other health effects that are unknown. Regardless, ATSDR concludes that this compound
does not present an apparent public health hazard because of the low concentrations,
relative low toxicity, low expected doses, and improbable exposures expected from the
media and the locations sampled. |
| - | 1,1'-sulfonylbis-4-chlorobenzene (SCB) was found in the water sample WP100 at 24J
mg/kg. EPA collected sample WP100 from Mount Blue Spring. The local public uses
this spring for a drinking water source by filling containers for use elsewhere. SCB is a
polymer approved by the FDA for use in reusable food containers. Limited toxicity data
were available to ATSDR on this compound. The National Institute of Health (1991)
reports an LD50 on mice (oral) at 24 grams per kilogram (gm/kg) and a Quantitative
Structure-Toxicity Relationship (QSTR) model predicts a rat LD50 of 2.3 gm/kg (Health
Designs 1998). On a relative scale, these LD50s are considered "moderately toxic"
(University of Nebraska-Lincoln 1997) or "slightly toxic" (University of Florida 1996)
similar in LD50s to common table salt, morphine, and silvex. One can only use these
relative LD50s as a general guide and they do not necessarily represent other nonlethal
health effects that are unknown.
The QSTR model also predicts potential developmental toxicity at a Lowest-Observed-Adverse-Effect Level (LOAEL) dose of 104 mg/kg. This concentration is approximately 100,000 times greater than expected human doses. ATSDR concludes that this compound does not present an apparent public health hazard
because of (1) FDA's determination, (2) the relative LD50s, (3) the high LOAEL, and (4)
the assumed lower frequency of ingestion from this water compared to tap water delivered
instantaneously at one's home. |
| - | Carbethoxyethylidine triphenylphosphorane (CT) was found in water samples WP100 and
WP102 at 12J and 6J µg/L. WP100 is located at Mount Blue Spring and WP102 is
located at a pond upgradient of the site. CT is used as a chemical intermediary (Stewart,
1997). Toxicologic data for CT is not available (Fisher-Scientific 1991). ATSDR
attempted to evaluate CT's toxicity through the QSTR model but the evaluation was not
possible because part of the molecule was not represented in the QSTR database.
As a result, we are unable to evaluate the exposure hazard to this chemical. However, this compound probably does not present a health hazard at 12 J µg/L because this concentration falls within typical ranges used by EPA as maximum contaminant levels (MCLs) for organics in drinking water. Additionally, these MCLs assume regular consumption of the water. Because the spring water is not used as frequently as tap water delivered instantaneously to one's home, the lower frequency of using the spring water means that a lower health risk occurs. Therefore, this chemical probably does not present a health hazard. Lastly, because CT was found in a hydraulic, upgradient, sample location and in Mount Blue Spring, but not onsite (during the April and September 1997 sampling), this compound probably did not originate from the site. Instead, CT may be naturally occurring, a result of contamination from the sampling and analysis procedures, or from another source. |
When comparing the April 1997 data with the September 1997 data, ATSDR identified many more TICs in the April 1997 data because the detection limits were 100 times lower. The concentrations of TICs in the April 1997 data were below 7 mg/kg in soils and below 20 µg/L for water. ATSDR did not evaluate the TICs from the April 1997 data because of the challenges in evaluating TICs, as discussed previously. Additionally, because of the sample locations, exposure would be infrequent, if it all. We did, however, evaluate the TICs in the water samples from Mount Blue Spring because of its use as a drinking water supply.
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